The invention relates to a pivotal-arm device for a scanning unit for recording and/or reading information on a disc-shaped record carrier. The device comprises a deck plate, a pivotal arm having means for securing the scanning unit, and pivotal-arm bearing means which pivotally supports the pivotal arm for pivotal movement about a pivotal axis, the bearing means comprising two bearings, disposed on opposite sides of the pivotal arm, a resilient element, which is secured to the deck plate, supports one of the bearings and urges the bearings towards one another.
Such a pivotal-arm device is known from European Patent Application No. 0074131 corresponding to U.S. Pat. No. 4,403,316 (hereby incorporated by reference). The known device is employed for moving and positioning an optical scanning unit relative to an optical disc and allows the scanning unit to make a limited pivotal movement. This pivotal movement is effected about a pivotal axis which extends parallel to the axis of rotation of a turntable for the optical disc, which turntable is supported in the stationary deck plate. The optical disc may be a video disc, an optical storage disc, or an optical audio disc. Two pre-stressed ball-bearings support the pivotal arm without play relative to the deck plate. The two ball-bearings, of which one bearing is secured directly to the deck plate and the other bearing is secured indirectly to the deck plate by means of a blade spring, should be aligned accurately relative to one another during assembly of the pivotal-arm device. Mounting the ball-bearings is therefore an intricate and time-consuming operation, which in combination with the rather expensive ball-bearings leads to an expensive pivotal-arm bearing means. Further, it has been found that during operation the known pivotal-arm device, which is arranged in a servo-control loop, has the disadvantage that undamped vibrations are produced in the pivotal-arm bearing means, which vibrations can set the deck plate with the optical disc and/or the pivotal arm in motion to such an extent that the servo control is disturbed.